This invention relates to an apparatus for storing energy mechanically and delivering it as electrical energy to a heating coil in a time of the order of a second.
Development of the Tokamak experimental power reactor has created the need for a device to couple electrical energy into a plasma for ohmic heating. It is proposed to accomplish the ohmic heating by transformer action from an ohmic heating coil in which an electric current of the order of 100,000 amperes is caused to reverse its direction in a time of the order of one second. During the time that the electric current in the ohmic heating coil is approaching and passing through zero, the electrical energy in the coil must be transferred out of the coil and returned to the coil in a short period of time. It is possible to dissipate that energy and to supply more for the buildup of current in the reverse direction but this is wasteful of energy and represents a situation to avoid. A static capacitor represents an improvement over the situation previously described in that the capacitor can store and return electrical energy. However, the requirements presently contemplated for the Tokamak experimental power reactor include the storage of energy to a value as high as 1000 megajoules with coil currents ranging between 40,000 and 100,000 amperes and coil voltages of 50,000 to 150,000 volts. The value of the capacitance must also be selected to tune with the inductance of the ohmic heating coil to permit a reversal of current in the desired time, of the order of one second. In particular, the value of the currents and the associated ohmic losses associated with the use of a static capacitor, and the fact that any capacitor so used must be capable of being charged in either direction result in a value of energy density that is unsatisfactorily low.
It is an object of the present invention to provide a better means of storing and returning electrical energy.
It is a further object of the present invention to provide an energy transfer and storage system to handle efficiently large amounts of electric energy.
It is a further object of the present invention to provide an energy transfer and storage system that will match the inductance of an ohmic heating coil to permit reversal of the current in the coil in one second.
Other objects will become apparent in the course of a detailed description of the invention.